Our 2 adult dogs aren't socialized and they have some PTSD from some prior fights with an aggressive dog. I'm cautiously integrating our new puppy with them, one at a time at first. 

1. The adults could hear and smell the puppy in the house for several days. They got used to the idea that there was a new dog.
2. I normalized wearing muzzles in the afternoon for about 3 days so that they wouldn't associate muzzles exclusively with the puppy.
3. I first introduced the older dog (not the one in the video) about 3 days in a row for 10–15 minute sessions. She started to seem blasé about the puppy. The third time was without the muzzle.
4. I introduced the younger adult, Pauline, yesterday (in the video). That went well too. This dog is not aggressive, but she has shown that she can "handle" an aggressive dog. (Pity the aggressive dog that attacks Pauline.) **So I've been treating Pauline as the more potentially dangerous dog.**
5. This video is from today. Still a lot of arousal, but also mutual bows. Pauline offering exploration. Puppy mouth contact that does not result in correction, freeze, or flinching. Sharing the water bowl.
6. I'm praising both of the adult dogs whenever look away or walk away from the puppy.

Once the adults are habituated, not-aroused, and bored, I will experiment with the three of them together, and ultimately remove the muzzles.

Thanks for your feedback.

Is this puppy integration going well?